Bone Markings

Bone Markings

Bones of the Axial Skeleton There are 80 bones in the central (axial) skeleton, comprising: Skull Vertebral column (including the sacrum) Ribs Sternum

Bones of the Skull The skull protects and supports the brain and special sense organs. Besides forming the large cranial cavity, the skull also forms several smaller cavities. Nasal cavity Orbits (eye sockets) Paranasal sinuses Small cavities which house organs involved in hearing and equilibrium

Bones of the Skull The bones of the skull are grouped into two categories: Cranial bones Facial bones Cranial bones Facial bones

Bones of the Skull 14 Facial Bones 8 Cranial Bones Mandible (1) Maxilla (2) Zygomatic bone (2) Nasal bones (2) Lacrimal bones (2) Palatine bones (2) Inf. Nasal conchae (2) Vomer (1) 8 Cranial Bones (Bones of the Braincase) Frontal bone (1) Parietal bone (2) Temporal bone (2) Occipital bone (1) Sphenoid bone (1) Ethmoid bone (1)

Bones of the Skull The braincase (neurocranium) has 8 bones: Single frontal, occipital (not shown on this graphic), ethmoid, and sphenoid bones, and paired temporal and parietal bones.

Bones of the Skull Frontal bone Parietal bone Sphenoid bone Temporal bone Ethmoid bone There are 8 bones in the cranium and 14 bones in the face = 22 bones in the skull Occipital bone

Bones of the Skull A suture is a “seam” – an immovable joint between bones of the skull. Coronal Suture Squamous Suture Lambdoidal Suture

Bones of the Skull Fontanels (“little fountains”) are soft, mesenchyme-filled spaces between cranial bones in babies. They will become suture joints in adults.

____ __ ___ ____ Bones of the Skull ____ __ ___ ____ Bones of the Skull The paranasal sinuses are prominent features of the frontal bone, ethmoid bone, sphenoid bone, and maxillary bones. Greater and lesser wings of the Sphenoid bone Sphenoid sinus Ethmoid bone (top) showing the “air cells” that make up the Ethmoid sinuses. Sphenoid bone (right)

Bones of the Skull With the exception of the ethmoid sinuses, the other paranasal sinuses are paired. They are lined with mucus membranes that humidify and warm the air. Reduce weight in the skull Help to resonate the sound of our voice

Representation of a Roman Arch Bones of the Skull Of the 8 cranial bones that fit together to form the braincase, the sphenoid bone is the “keystone”. Like the keystone of a roman arch, the sphenoid is the “center brick” that balances the outward thrust of the other bones. Representation of a Roman Arch

Bones of the Skull The Sphenoid bone The rest of the braincase bones are dependent for support on the sphenoid bone (with its greater and lesser wings).